1. Technical Field
The present invention relates to an optical disk device, and in particular to movement of a disk tray.
2. Related Art
Conventionally, a technique is proposed for adjusting a movement velocity of a disk tray. JP 2-144159 U discloses a technique wherein an actual movement time between an ejected position and stored position of a disk tray is measured, and an information signal for correcting a movement time of the disk tray is output to a disk tray driving motor controller based on a comparison result between the measured actual movement time and a movement reference time.
JP 2001-216702 A discloses that, when a preset movement velocity of a placement tray cannot be obtained when the placement tray is slid, an instruction signal for suitably correcting the applied voltage to the output motor is output from a calculator to a drive power supply. JP 2003-281806 A discloses that a loading time or an ejection time of a disk tray is measured, and when the disk tray loading time or the disk tray ejection time is not within a predetermined range, the motor is controlled so that the drive voltage of the loading motor is changed, and the disk tray loading time or the disk tray ejection time is within the predetermined range. JP 2008-34030 A discloses that a time from pressing of an open switch of a disk tray to a time when a switch which detects that the disk tray is opened is switched OFF is measured, and when the switch is not switched OFF within a certain time period from start of the open/close operation of the disk tray, it is judged that dust or the like is adhered to the moving unit and the open/close operation of the disk tray is slow or stopped, and the drive voltage applied to the motor is increased.
In a processing system or the like which automatically transports an optical disk to an optical disk device, the disk tray must be highly precisely positioned, in order to reliably place the optical disk on the disk tray. If the position of the disk tray is unstable, the optical disk may deviate from the disk tray or ejection becomes difficult. In order to improve the position precision of the disk tray, there is known a method in which the disk tray is moved until the disk tray contacts a mechanical stopper, when the disk tray is to be ejected.
In general, in a disk tray type loading mechanism, switches are provided which detect a loading completion position (close position) and ejection completion position (open position), respectively. When ejection is detected by the switch, the disk tray is stopped. When the disk tray collides with the mechanical stopper, a failure such as a boss fracture may occur due to the shock, and thus the disk tray is controlled so that a suitable margin is provided from the switching ON of the switch to the mechanical stopper, to avoid collision with the mechanical stopper. However, because there is a variation in the position where the switch is switched ON or in the actual distance the disk tray travels after the switch is switched ON, the positional precision of the disk tray is not high. Therefore, the disk tray is intentionally brought into contact with the mechanical stopper, to secure positional precision. In order to prevent failure due to collision with the mechanical stopper, the disk tray is driven at a relatively slow velocity from the time when the switch is switched ON to the time when the disk tray contacts the mechanical stopper.
However, when the frictional force of the disk tray changes or the power supply voltage of the device changes due to deterioration with time, the movement velocity of the disk tray would vary even when the disk tray is driven in the same manner. In some cases, the disk tray may stop in the middle without contacting the mechanical stopper, and thus there is a problem in that the positional precision of the disk tray cannot be secured.